It is necessary to conduct craniotomy by removing a necessary portion of a skull after incising a scalp in a case of operating a damaged portion in a brain. A range to conduct the craniotomy depends on a disorder and a portion where a tumor exists due to a brain tumor.
There are several kinds of methods as shown in patent document 1 as a representative method for conducting the craniotomy. For example, one of the methods is to perforate several relatively big holes (burr holes) along a range of the skull where the craniotomy is to be conducted by the use of a perforator as being a drill configured for boring the skull and then to cut the skull along a line connecting these burr holes by the use of a rotary blade of a craniotome in a shape of an end mill head.
An automatic light interception mechanism is arranged to perforate the burr holes in the skull in order to avoid further reaching deeper of a distal end of the drill at a time when the distal end of the drill penetrates the skull. Then the rotary blade is inserted into the burr hole that has been perforated as mentioned above and the skull is cut along a rotary range that has been previously set. Hereinafter there is a case that a portion of the skull cut in the predetermined range is termed as a bone flap for simplification.
After the bone flap is removed and the damaged portion in the brain is operated on, the bone flap is to be returned to the cut portion so as to close the skull. In order to close the skull, the bone flap is fixed to the skull by screwing both the bone flap and the skull so as to not to cave in by means of a fixing member comprising a plate of titanium lying between the bone flap and its circumference of the skull.
In addition to the above, there is a method for cutting the skull called a wire saw craniotomy which is another method for craniotomy. This method is to cut the skull between the adjacent burr holes by the use of a metal jigsaw.
Furthermore, there is also another method called a trephine craniotomy to cut the skull in a circle with a circular saw by rotating its circular blade.
Patent document 1: Japan Patent Laid-open number 2002-238911